Ol Veretin

Two-loop QCD corrections of the massive fermion propagator

Abstract The off-shell two-loop correction to the massive quark propagator in an arbitrary covariant gauge is calculated and results for the bare and renormalized propagator are presented. The calculations were performed by means of a set of new generalized recurrence relations proposed recently by one of the authors [Nucl. Phys. B 502 (1997) 455]. From the position of the pole of the renormalized propagator we obtain the relationship between the pole mass and the MS mass. This relation confirms the known result by Gray et al. [Z. Phys. C 48 (1990) 673; C 52 (1991) 111]. The bare amplitudes are given for an arbitrary gauge group and for arbitrary space-time dimensions.

MS vs. pole masses of gauge bosons: electroweak bosonic two-loop corrections

The relationship between MS and pole masses of the vector bosons Z and W is calculated at the two-loop level in the Standard Model. We only consider the purely bosonic contributions which represent a gauge invariant subclass of diagrams. All calculations were performed in the linear Rξ gauge with three arbitrary gauge parameters utilizing the method of asymptotic expansions. The results are presented in analytic form as series in the small parameters sin 2 �W and the mass ratio m 2 /m 2 . We also present the corresponding on-shell mass counter-terms for the massive gauge bosons, which will be needed for the calculation of observables at two-loops in the on-shell renormalization scheme.The relationship between MS and pole masses of the vector bosons Z and W is calculated at the two-loop level in the Standard Model. We only consider the purely bosonic contributions which represents a gauge invariant subclass of diagrams. All calculations were performed in the linear

Single-scale diagrams and multiple binomial sums

R_\xi

TESTING NON-PERTURBATIVE STRONG INTERACTION EFFECTS VIA THE ADLER FUNCTION

gauge with three arbitrary gauge parameters utilizing the method of asymptotic expansions. The results are presented in analytic form as series in the small parameters

The differential equation method: calculation of vertex-type diagrams with one non-zero mass

\sin^2\theta_W

Non factorizable O(ααs) corrections to the process

and mass ratio

Large mass expansion versus small momentum expansion of Feynman diagrams

m_Z^2/m_H^2

Pole masses of gauge bosons: 2-loop electroweak corrections

. As a byproduct we obtain the bosonic two-loop contributions to the renormalization of the weak mixing parameter

Non factorizable

\sin^2\theta_W

O(\alpha\alpha_s)

and of the Fermi constant. The running of Fermi constant will become important at high energy colliders.